1. Technical Field
The present disclosure relates to a multi-sector radar including a plurality of sector radars that transmit high-frequency signals (e.g., millimeter waves).
2. Description of the Related Art
For detecting the presence/absence of targets (e.g., automobiles or people) in a wide angular range, a measurement method using a plurality of radar devices (each of which is hereinafter referred to as a “sector radar”) using code sequences having mathematical orthogonality (see, for example, Complementary Sets of Sequences IEEE TRANSACTIONS ON INFORMATION THEORY, Vol. IT-18, No. 5, September 1972) has been proposed (see, for example, Japanese Unexamined Patent Application Publication No. 61-096482). Japanese Unexamined Patent Application Publication No. 61-096482 discloses, for a plurality of (e.g., two) sector radars, a radar system that suppresses interference between the sector radars by using, as transmission codes, complementary codes having mathematical orthogonality.
The present inventors have studied a multi-sector radar including a plurality of sector radars that transmit high-frequency signals (e.g., in a millimeter wave band). Japanese Unexamined Patent Application Publication No. 61-096482, however, does not consider the operation of the multi-sector radar when phase rotation occurs in reception signals (e.g., when a target moves during measurement) with changes in the Doppler frequency. Thus, the multi-sector radar in the related art has a problem in that, when phase rotation occurs in reception signals with changes in the Doppler frequency, a correlation characteristic of the reception signals deteriorates.